1. Field of the Invention
The present invention relates to compositions suitable for use in refrigeration and air conditioning apparatus comprising 1,1,1,3,3-pentafluorobutane and at least one hydrofluorocarbon, N-(difluoromethyl)-N,N-dimethylamine, or 1,1,1,2,2-pentafluoro-2-[(pentafluoroethyl)thio]ethane or combinations thereof. Further, the present invention relates to compositions suitable for use in refrigeration and air-conditioning apparatus employing a centrifugal compressor comprising 1,1,1,3,3-pentafluorobutane and at least one hydrofluorocarbon, N-(difluoromethyl)-N,N-dimethylamine, or 1,1,1,2,2-pentafluoro-2-[(pentafluoroethyl)thio]ethane or combinations thereof. The compositions of the present invention may be azeotropic or near azeotropic in nature and are useful in processes for producing refrigeration or heat or as heat transfer fluids.
2. Description of Related Art
The refrigeration industry has been working for the past few decades to find replacement refrigerants for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) being phased out as a result of the Montreal Protocol. The solution for most refrigerant producers has been the commercialization of hydrofluorocarbon (HFC) refrigerants. The new HFC refrigerants, HFC-134a being the most widely used at this time, have zero ozone depletion potential and thus are not affected by the current regulatory phase out as a result of the Montreal Protocol.
Further environmental regulations may ultimately cause global phase out of certain HFC refrigerants. Currently, the automobile industry is facing regulations relating to global warming potential for refrigerants used in mobile air-conditioning. Therefore, there is a great current need to identify new refrigerants with reduced global warming potential for the automobile air-conditioning market. Should the regulations be more broadly applied in the future, an even greater need will be felt for refrigerants that can be used in all areas of the refrigeration and air-conditioning industry.
Currently proposed replacement refrigerants for HFC-134a include HFC-152a, pure hydrocarbons such as butane or propane, or “natural” refrigerants such as CO2 or ammonia. Many of these suggested replacements are toxic, flammable, and/or have low energy efficiency. Therefore, new alternatives are constantly being sought.
The object of the present invention is to provide novel refrigerant compositions and heat transfer fluids that provide unique characteristics to meet the demands of low or zero ozone depletion potential and lower global warming potential as compared to current refrigerants.